JPH0942436A - Shift control device for automatic transmission for vehicle - Google Patents

Abstract

(57) [Abstract] [Purpose] Shift control of an automatic transmission for a vehicle that prevents shift shock even if a clutch-to-clutch down shift during coasting is executed when the low drive torque start mode is selected. Provide a device. [Structure] When it is determined that the low drive torque starting mode is selected, the shift pattern changing unit 162 selects the second shift diagram in place of the first shift diagram.
If the sequence shift means 166 determines from the second shift diagram that the clutch-to-clutch down shift from the first gear to the second gear during coasting, the first shift After the gear shift from the gear stage to the third gear stage is executed, the gear shift to the second gear stage is executed. Therefore, when the low drive torque start mode is selected, the shift is executed based on the second shift diagram to enable the low drive torque start, and
Clutch-to-clutch Clutch coast down Gear shift shock and drivability deterioration due to gear shift are eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift control device for an automatic transmission for a vehicle.

[0002]

2. Description of the Related Art Instead of abolishing a one-way clutch for the purpose of downsizing and weight reduction, the hydraulic pressure of one friction engagement device (clutch or brake) is released and at the same time the other friction engagement device (clutch or brake) is released. There is an automatic transmission for a vehicle of a type in which a so-called clutch-to-clutch shift in which a predetermined gear is switched to another gear by increasing hydraulic pressure is executed. In such an automatic transmission for a vehicle, the release pressure (drain) of one friction engagement device is generated so that a period in which one and the other friction engagement devices have an engagement torque is generated during the clutch-to-clutch shift period. The pressure is adjusted, or the engagement pressure supplied to the other frictional engagement device is adjusted. At this time, when the timings of decrease and increase of the engagement torque do not mesh properly with the one and the other friction engagement devices, that is, when the decrease of the engagement torque of the one friction engagement device is too fast or the friction engagement of the other friction engagement device If the engagement torque of the device rises too slowly, for example, a temporary overshoot of the engine rotation speed occurs, and if the engagement torque of one friction engagement device decreases too slowly or the friction of the other friction engagement device decreases. If the engagement torque of the engagement device rises too fast, a temporary sharp drop in the output torque of the automatic transmission, which is so-called tie-up, occurs.

[0003]

In the clutch-to-clutch shift described above, the engagement torque of the disengagement side friction engagement device and the engagement torque of the engagement side friction engagement device are increased at appropriate timings. In order to smoothly disengage or engage the friction engagement device by executing the above, relatively complicated control is required, but especially in the clutch-to-clutch down shift during coasting, There was a problem in that a shift shock also occurred in the control, and the driving feeling was impaired. For example, while detecting the degree of progress of the shift using the relationship between the input shaft rotation speed and the output shaft rotation speed of the automatic transmission,
It is possible to smoothly engage the friction engagement device on the engagement side by outputting an appropriate control pressure from the solenoid valve and adjusting the engagement pressure by the pressure control valve. For example, in a coasting traveling state such as a minute driving state or a non-driving state in which the driving torque of the vehicle, that is, the input torque of the automatic transmission is less than or equal to a predetermined value, the relationship between the input shaft rotation speed and the output shaft rotation speed is broken and the gear shifting In some cases, it is not possible to accurately detect the degree of progress of the above, the dispersion of the engagement pressure of the friction engagement device regulated by the pressure regulating valve becomes large, and a shift shock is likely to occur in the clutch-to-clutch down shift.

On the other hand, when the vehicle is running in a predetermined running state such as coasting, the shift line is set so as to shift down from the first gear to the third gear one step below the second gear. It is conceivable to use the set first shift diagram during normal traveling. In such a case, the clutch-to-clutch down shift during coasting is uniformly avoided, so the driving feeling is not impaired by the shift shock due to the clutch-to-clutch down shift. When the low drive torque start mode in which the vehicle is started with low drive torque is selected, the vehicle cannot be started in the second gear.

Further, when the low drive torque starting mode is selected, in order to start at the second gear,
In addition to the first shift diagram, the second shift diagram in which the shift line for setting the clutch-to-clutch down shift from the first gear stage to the second gear stage is set during coasting is also used. It is possible to do it. However, in such a case, when the low drive torque start mode is selected, the clutch-to-clutch down shift during coasting is allowed, so that a shift shock may occur. was there.

The present invention has been made in view of the above circumstances. An object of the present invention is to perform clutch-to-clutch down shift during coasting when the low drive torque starting mode is selected. An object of the present invention is to provide a shift control device for an automatic transmission for a vehicle, in which a shift shock is prevented even if it is performed.

[0007]

The gist of the present invention for achieving the above object is to release the hydraulic pressure of one friction engagement device and simultaneously increase the hydraulic pressure of the other friction engagement device. In a vehicle automatic transmission in which a clutch-to-clutch down shift is performed, in which a predetermined first gear is switched to a second gear that is one step lower than the predetermined first gear,
A shift control device comprising shift control means for executing a shift determined based on an actual vehicle traveling state from a preset shift diagram, wherein (a) a low drive torque starting mode is selected. Low drive torque starting determination means for determination,
(b) If it is determined by the low drive torque start determination means that the low drive torque start mode is selected,
The first shift pattern that shifts down from the first gear to the third gear that is one step lower than the second gear during predetermined traveling is replaced with the first shift pattern during the predetermined traveling. From the second shift pattern selected by the shift pattern changing means for selecting the second shift pattern for performing the clutch-to-clutch down shift from the gear position to the second gear position, (c) the second shift pattern selected by the shift pattern changing means, When the clutch-to-clutch down shift from the first gear to the second gear is determined during the predetermined traveling, the shift from the first gear to the third gear is performed. And a sequence shift means for executing the shift to the second gear after the shift is executed.

[0008]

In this way, when the low drive torque start mode is determined to have been selected by the low drive torque start determination means, the shift pattern changing means changes the first drive speed during the predetermined travel. In place of the first shift pattern for downshifting from the gear stage to the third gear stage which is one stage lower than the second gear stage, the first gear stage to the second gear stage may be changed during the predetermined traveling. The second shift pattern for shifting the clutch to clutch down shift to is selected. If the sequence shift means determines from the second shift pattern that the clutch-to-clutch down shift from the first gear to the second gear during the predetermined traveling is performed, the first shift is performed. After the gear shift from the first gear to the third gear is performed, the gear shift to the second gear is performed. Therefore, during normal traveling in which the low drive torque starting mode is not selected, the gear shift is executed based on the first gear shift pattern, so that clutch-to-clutch down gear shift is avoided as much as possible to ensure drivability. When the low drive torque start mode is selected, the shift is executed based on the second shift pattern and the clutch-to-clutch down shift during the predetermined traveling is allowed, so that the low drive torque start is possible. At the same time, the clutch-to-clutch down shift is performed by the sequence shifting means after the shift from the first gear to the third gear is performed, and then the shift to the second gear. The shift shock and the decrease in drivability caused by it are eliminated.

[0009]

Another aspect of the present invention is preferably that the predetermined running is coasting of the vehicle such as a minute driving state in which the driving torque of the vehicle is a predetermined value or less or a non-driving state of the vehicle,
A clutch-to-clutch coast-down shift determining means for determining from the second shift pattern that the clutch-to-clutch down shift determined based on the vehicle state represented by the engine load and the vehicle speed is during coasting. It is provided. The sequence shift means changes from the first gear stage to the third gear stage when the clutch-to-clutch coast-down shift determination means determines that the clutch-to-clutch down shift is during coasting. The shift to the second gear is performed after the shift to.

Further, preferably, a vehicle speed judging means for judging whether or not the vehicle speed is equal to or lower than a preset low vehicle speed judging reference value is provided, and the sequence speed changing means is arranged from the first gear stage to the first gear stage. After performing the shift to the third gear, the shift to the second gear is performed when the vehicle speed determination unit determines that the vehicle speed is equal to or lower than a preset low vehicle speed determination reference value. . As a result, there is an advantage that the second gear is surely established before the vehicle is stopped.

Further, preferably, there is provided a drive traveling determination means for determining whether or not the vehicle is in the drive traveling state in which the throttle valve opening, the engine load, or the output torque of the engine is a predetermined value or more, and the sequence described above. Even if the vehicle speed determination means does not determine that the vehicle speed is equal to or lower than the preset low vehicle speed determination reference value, the speed change means determines the second gear when the vehicle drive determination is determined by the drive travel determination means. Shift to the next gear. Thus, in the low drive torque starting mode, when the accul pedal is stepped on while the vehicle is running, the second gear can immediately start the vehicle without waiting until the vehicle speed becomes equal to or lower than the preset low vehicle speed determination reference value. There are advantages.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a skeleton view showing an example of an automatic transmission for a vehicle which is shift-controlled by a shift control device according to an embodiment of the present invention. In the figure, the output of the engine 10 is
It is input to the automatic transmission 14 via the torque converter 12 and transmitted to the drive wheels via a differential gear unit and an axle (not shown).

The torque converter 12 is used for the engine 1
Pump impeller 18 connected to crankshaft 16
, A turbine runner 22 connected to the input shaft 20 of the automatic transmission 14, a lock-up clutch 24 directly connecting between the pump impeller 18 and the turbine runner 22, and a one-way clutch 26 that prevents rotation in one direction. And a stator 28 that is in the position.

The automatic transmission 14 includes a first transmission 30 for switching between high and low gears, and a second transmission 32 for switching between a reverse gear and four forward gears. The first transmission 30 includes an HL planetary gear device 34 including a sun gear S0, a ring gear R0, and a planet gear P0 rotatably supported by the carrier K0 and meshed with the sun gear S0 and the ring gear R0, a sun gear S0, and a carrier. The clutch C0 and the one-way clutch F0 are provided between the sun gear S0 and the housing 41, and the brake B0 is provided between the sun gear S0 and the housing 41.

The second transmission 32 has a first planetary gear unit 36 comprising a sun gear S1, a ring gear R1, and a planetary gear P1 rotatably supported by the carrier K1 and meshed with the sun gear S1 and the ring gear R1.
, Sun gear S2, ring gear R2, and carrier K
2 and a second planetary gear unit 38, which is rotatably supported by the sun gear S2 and a ring gear R2 and is meshed with the sun gear S2 and the ring gear R2, and the sun gear S3, the ring gear R3, and the carrier K3, which are rotatably supported by the sun gear S2. S3 and a third planetary gear set 40 including a planet gear P3 meshed with the ring gear R3.

The sun gear S1 and the sun gear S2 are integrally connected to each other, the ring gear R1, the carrier K2 and the carrier K3 are integrally connected, and the carrier K3 is connected to the output shaft 42. Further, a ring gear R2 is integrally connected to the sun gear S3. A clutch C1 is provided between the ring gear R2 and the sun gear S3 and the intermediate shaft 44, and the sun gear S1 and the sun gear S3 are provided.
A clutch C2 is provided between the shaft 2 and the intermediate shaft 44. A band-type brake B1 for stopping rotation of the sun gear S1 and the sun gear S2 is provided on the housing 41.
It is provided in. A one-way clutch F1 is provided between the housing 41 and the sun gear S1 and the sun gear S2.
And the brake B2 are provided in series. The one-way clutch F1 is configured to be engaged when the sun gear S1 and the sun gear S2 try to reversely rotate in the direction opposite to the input shaft 20.

A brake B3 is provided between the carrier K1 and the housing 41, and a brake B4 and a one-way clutch F2 are provided between the ring gear R3 and the housing 41 in parallel. This one-way clutch F
2 is configured to be engaged when the ring gear R3 attempts to rotate in the reverse direction.

In the automatic transmission 14 configured as described above, for example, according to the operation table shown in FIG. 2, the automatic transmission 14 is switched to one of the first reverse gear and the five forward gears having sequentially different speed ratios. In FIG. 2, a circle indicates an engaged state, a blank indicates a released state, and a ● indicates an engaged state during engine braking. As is clear from FIG. 2, between the second speed and the third speed, the clutch toe achieved by releasing one of the brake B3 and the brake B2 and simultaneously engaging the other. In the case of clutch shift, for example, 3 → 2 shift (clutch to clutch down shift), the period during which the brake B2 that is in the process of releasing the engagement torque and the period during which the brake B3 that is in the process of applying the engagement torque are over. I can be wrapped. In addition, 2 → 1 from the second gear stage or the third gear stage to the first gear stage
The shift or the 3 → 1 shift can be achieved only by releasing the second gear stage or the third gear stage. Further, in the first gear, the engine brake does not act due to the idling of the one-way clutch F2.

As shown in FIG. 3, the engine 10 of the vehicle is
The intake pipe is operated by an accelerator pedal 50
First throttle valve 52 and throttle actuator 54
The second throttle valve 56 that is electrically operated by
Is provided. Also, the rotation speed N of the engine 10_ETo
Engine rotation sensor 58 for detecting, intake of engine 10
The intake air amount sensor 60 for detecting the air amount Q,
Temperature T_AIntake air temperature sensor 62 for detecting the
The opening θ of the throttle valve 52_THThrottle sensor to detect
Rotation speed N of the output shaft 42_OUTDetects vehicle speed V from
Vehicle speed sensor 66, cooling water temperature T of engine 10_WTo
Cooling water temperature sensor 68, which detects the operation of the brake
Brake switch 70, shift lever 72 operating position
P_SHAn operation position sensor 74 for detecting
From those sensors, the engine speed N_E, Inhalation
Air amount Q, intake air temperature T_A, Opening of the first throttle valve
θ _TH, Vehicle speed V, engine cooling water temperature T_W, Brake operation
State BK, shift lever 72 operating position P_SHSignal that represents
Is an electronic control unit for engine 76 and an electronic control unit for shifting.
It is designed to be supplied to the storage 78. Also turbine
Rotation speed N_TThat is, the rotation speed N of the clutch C0_C0Inspect
The turbine rotation speed N is output from the turbine rotation sensor 73.
_T(= N_C0) And hydraulic oil of the hydraulic control circuit 84
Temperature T_OILFrom the oil temperature sensor 75 that detects the
_OILIs supplied to the electronic shifting control device 78.
You. In addition, low driving from the snow mode selection switch 77
The signal SN indicating the start of the dynamic torque is the electronic control unit 7 for shifting.
8 is supplied.

Further, as shown in FIG. 4, the shift lever 72 is operated to the P range, the R range, the N range, the D range, the 4 range, the 3 range, the 2 range, and the L range located in the front-rear direction of the vehicle. At the same time, the support mechanism is configured such that the range between the D range and the 4 range and the range between the 2 range and the L range are operated in the left-right direction of the vehicle.

The engine electronic control unit 76 includes a CPU,
A so-called microcomputer having a RAM, a ROM, and an input / output interface, the CPU processes an input signal according to a program stored in the ROM in advance while utilizing a temporary storage function of the RAM, and executes various engine controls. For example, the fuel injection valve 80 is controlled to control the fuel injection amount, the igniter 82 is controlled to control the ignition timing, a bypass valve (not shown) is controlled to control the idle speed, and the throttle actuator is controlled to control the traction. The second throttle valve 56 is controlled by 54, and when the engine speed N _E enters a preset overspeed region (for example, the red zone), the fuel injection valve 80 is shut off and the engine speed N _E is further increased. Suppress. The engine electronic control unit 76 is communicably connected to the shift electronic control unit 78, and a signal required for one is appropriately transmitted from the other.

The electronic control unit 78 for shifting is also a microcomputer similar to the above, and the CPU processes input signals in accordance with a program stored in the ROM in advance while utilizing the temporary storage function of the RAM. Of each solenoid valve or linear solenoid valve. For example,
The electronic shift control device 78 generates a throttle pressure P _TH having a magnitude corresponding to the opening degree θ _TH of the first throttle valve 52 and controls the accumulator back pressure by a linear solenoid valve.
SLT drives the linear solenoid valve SLU respectively to control the engagement, release, slip amount and shift of the clutch-to-clutch of the lockup clutch 24. In addition, the electronic shift control device 78 uses the pre-stored shift map to determine the gear position of the automatic transmission 14 and the lockup clutch 2 based on the actual throttle valve opening θ _TH and the vehicle speed V.
The engagement state of No. 4 is determined, and shift control is performed to drive the solenoid valves S1, S2, S3 so that the determined gear stage and engagement state are obtained. Further, the electronic shift control device 78, during the clutch-to-clutch shift, sets the input shaft rotation speed N _in and the output shaft rotation N _in of the automatic transmission 14 so that the engagement torques of the brakes B2 and B3 appropriately overlap. The output pressure P _SLT of the linear solenoid valve SLU and the linear solenoid valve _SLT is controlled according to the signal level of the shift while utilizing the relationship of the speed N _out .

5 and 6 show the hydraulic control circuit 84.
Are shown. 1-2 shift valves 88 and 2 shown
The -3 shift valve 90 is based on the output pressures of the solenoid valves S1 and S2, when shifting from the first gear to the second gear and when shifting from the second gear to the third gear. In the above, the switching valves are switched respectively, and the numerical value indicating the switching position indicates the gear position. The forward range pressure P _D is a pressure generated from a manual valve (not shown) when the shift lever 72 is operated to the forward range (D, 4, 3, 2, L), and is controlled by a regulator valve (not shown). The line pressure P _L, which is adjusted to a high level according to the opening, is used as the source pressure.

When a shift output for switching from the first gear to the second gear is issued, the forward range pressure P
_D is supplied to the brake B3 and the damper 94 via the 1-2 shift valve 88, the 2-3 shift valve 90, the oil passage L01, the B3 control valve 92, and the oil passage L02. Further, when the shift output for switching from the second gear to the third gear is output, the forward range pressure P _D becomes the 2-3 shift valve 9
At the same time as being supplied to the brakes B2 and B2 accumulators 100 through 0 and the oil passage L03, the working oil in the brake B3 is returned to the oil passages L02, B3 control valve 92, oil passage L01, 2-3 shift valve 90, and returned. Oil passage L04, 2-
3 Pressure valve is drained through the timing valve 98,
Branch oil passages L05 and B2 branched from the return oil passage L04
It is adapted to be rapidly drained through the orifice control valve 96.

Back pressure chamber 1 of the B2 accumulator 100
00 of _B, the output pressure P _SLT of the output pressure P _SLT and the linear solenoid valve SLT for the linear solenoid valve SLT is supplied during each shift.

The B3 control valve 92 is connected to the oil passage L0.
Spool valve element 104 that opens and closes between valve 1 and oil passage L02
And the same as the spool valve element 104 with the spring 106 interposed.
Provided at the center and having a diameter larger than that of the spool valve element 104.
The plunger 108 and the spring 106 are housed therein,
When the 2-3 shift valve 90 is switched to the third speed side
Forward range pressure P output from it_DVia oil passage L07
Oil chamber 110 and shaft end of plunger 108
The output pressure P of the linear solenoid valve SLU _SLUTo
And a receiving oil chamber 112. Therefore, B3
In the process of establishing the second gear, the control valve 92
Output pressure P of linear solenoid valve SLU_SLUAccording to spoo
Position the valve valve 104 in the open position shown on the left side of the center line.
Perform the first fill early on and then
Supply the hydraulic oil from the oil passage L01 to the oil passage L02, or
Causes the hydraulic oil in the oil passage L02 to flow out to the discharge oil passage L06.
As a result, the engagement pressure P in the brake B3_B3The rise of
From Equation 1, the output pressure P_SLUAdjust the pressure based on. Ma
In addition, the B3 control valve 92 is a gear higher than the third gear.
In the gear stage, the oil is supplied from the 2-3 shift valve 90 to the oil chamber 110.
Forward range pressure P_DIn accordance with the spool valve 104
Lock it in the open position shown to the left of the core. This is B3
Oil chamber 112 of control valve 92 and 2-3 timing valve
Since it is connected to the oil chamber 138 of 98, the second →
In the 3-speed state, the oil chamber 112 of the B3 control valve 92
Block the volume change of the
This is to prevent the pressure regulating operation from being affected. What
In equation 1, S₁ And S₂Is the plunger 10
8 is a cross-sectional area of 8 and the spool valve element 104.

[0028]

[ _Equation 1] P _B3 = P _SLU · S ₁ / S ₂

The B2 orifice control valve 96 is
Rake B2 and B2 accumulator 100 and oil passage L0
3 and at the same time discharge oil passage L06 and drain
A spool valve 114 that opens and closes between the
Attach the pool valve 114 toward the first drain position.
The spring 116 to be urged and the shaft end of the spool valve 114
And the output pressure P of the third solenoid valve S3_S33-4 shifts
And an oil chamber 120 which receives the oil through a valve 118.
You. As a result, the third solenoid valve S3 can be used, for example, during a 3 → 2 shift.
Is turned on and its output pressure P_S3Supplied to oil chamber 120
The spool valve 114 prevents the brake
B2 and between B2 accumulator 100 and oil passage L03
Open between them brake B2 and B2 accumulate
Fur that quickly discharges hydraulic oil from the
Stodrain operation is performed. Also in 1 → 2 shift
Indicates that the third solenoid valve S3 is turned off and its output pressure
P _S3Is supplied to the oil chamber 120 so that the B3 control
Operation discharged from the pressure regulating operation of the roll valve 92
A discharge oil passage L06 for discharging oil and a drain port 113
Is opened to adjust the pressure of the B3 control valve 92
Is permitted, but when the 1 → 2 shift is completed, the third solenoid valve S
3 is turned on, the discharge oil passage L06 and the drain port 1
13 is closed by closing B3 control valve
The pressure regulation operation of 92 is stopped.

The 2-3 timing valve 98 is involved in shifting from the second gear to the third gear, and regulates the release pressure from the brake B3 from the linear solenoid valve SLU according to the output pressure P _SLU. Function as. That is, 2-
3 timing valve 98, 2 → 3 forward range pressure P _D is output from the 2-3 shift valve 90 when the shift is outputted 3-4 shift valve 118 and the solenoid relay valve 122
The supply port 124, the drain port 126, and the oil passage L04, which are supplied through the brake B3, are connected to the supply port 124 or the drain port 126.
Spool valve 128 that regulates the pressure P _B3 during the drain period of
And a first concentrically provided with a spool valve element 128 via a spring 130 and having the same diameter as the spool valve element 128.
The plunger 132 and the spool valve element 128 are provided concentrically with the spool valve element 128 so as to be in contact with one end thereof.
A second plunger 134 having a diameter larger than 28, houses a spring 130, an oil passage L08 to the forward range pressure P _D is output therefrom when the 2-3 shift valve 90 is switched to the second speed side And an oil chamber 138 provided at the shaft end of the first plunger 132 for receiving the output pressure P _SLU from the linear solenoid valve SLU.
And an oil chamber 140 provided at the shaft end of the second plunger 134 for receiving the hydraulic pressure P _B2 in the brake B2 and a feedback oil chamber 142 for receiving the feedback pressure.

Therefore, the sectional area of the spool valve element 128 and the first plunger 132 is S ₃ , and the spool valve element 12 is
8, the land area on the second plunger 134 side is S ₄ ,
When the cross-sectional area of the second plunger 134 and S _5, 2 → 3
Brake B in the release process when the gearshift output is output
The pressure P _B3 of No. 3 decreases according to the increase of the engagement pressure P _B2 of the brake B2 from the mathematical expression 2 by the pressure adjustment operation by the 2-3 timing valve 98, and the output pressure P of the linear solenoid valve SLU.
_The pressure is adjusted to increase according to the _SLU .

[0032]

## EQU2 ## P _B3 = P _{SLU .S 3} / (S ₃ −S ₄ ) −P _{B2.
S 5 / (S 3 -S 4} )

Further, when the forward range pressure P _D output from the 2-3 shift valve 90 switched to the second speed side is supplied to the oil chamber 136, the 2-3 timing valve 98 outputs the spool valve. The child 128 is adapted to be locked. This is also the oil chamber 138 of the 2-3 timing valve 98 and B
Since the oil chamber 112 of the third control valve 92 is connected, the change in the volume of the oil chamber 138 of the 2-3 timing valve 98 is prevented in the first speed and the second speed, and the B3 control valve 92 is closed. This is so as not to affect the pressure regulation operation.

[0034] C0 exhaust valve 150, the output pressure P _S4 of the third but brought into the closed position in accordance with the hydraulic pressure in the output pressure P _S3 and the oil passage L01 of the solenoid valve S3, the fourth solenoid valve S4
Accordance with the spool 152 is caused to position to the open position, the line pressure P _L supplied via it when the 4-5 shift valve (not shown) is in switching state of the following fourth speed, the second speed And clutch C at times other than the fifth speed
0 and the C0 accumulator 154.

7 and 8 show an electronic control unit 7 for shifting.
8 shows a first shift diagram and a second shift diagram which are stored in advance in the ROM of FIG. The first shift diagram of FIG. 7 and the second shift diagram of FIG. 8 show the first shift pattern and the second shift pattern.
Although a plurality of downshift lines and a plurality of upshift lines for determining each shift are provided to drive the vehicle in a shift pattern, in the first shift diagram of FIG. The shift line and the 3 → 2 downshift line are the 2 → 1 downshift line in the second shift diagram of FIG.
A 1 → 2 upshift line and a 3 → 2 downshift line are illustrated. The above-described first shift diagram is used in normal running in which the snow mode for starting the vehicle with a low driving torque is not selected, for example, 2 → 1.
Since the low throttle opening side of the downshift line and the 3 → 2 downshift line is shared, the 3 → 2 shift, that is, the clutch-to-clutch down shift, in coasting running conditions such as small drive running and non-drive running Are being avoided. Further, the above-mentioned second shift diagram is used in special running in which the snow mode for starting the vehicle with a low driving torque is selected, and 2 → 1
By removing the low throttle opening side of the downshift line and the 1 → 2 upshift line, the 3 → 2 shift, that is, the clutch-to-clutch down shift is allowed in the coasting running condition such as the minute drive running or the non-driving running. Thus, the second speed gear is formed when the vehicle is stopped, and the vehicle can be restarted at the second speed.

FIG. 9 is a functional block diagram for explaining the main part of the control function of the electronic shift control device 78. The shift control means 158 determines the shift of the automatic transmission 14 based on the actual throttle valve opening θ _TH and the vehicle speed V from the previously stored first shift diagram or second shift diagram, and executes the shift. By executing the shift output to operate any one of the solenoid valves S1, S2, S3 for operating the vehicle, the vehicle is run in accordance with the first shift pattern or the second shift pattern.

The low drive torque start determining means 160 determines that the low drive torque start mode has been selected by the snow mode selection switch 77. When the low drive torque start determination means 160 determines that the low drive torque start mode is selected, the shift pattern changing means 162 is a shift diagram for use in the shift control means 158 as shown in FIG. By selecting the second shift diagram of FIG. 8 instead of the first shift diagram, the vehicle is driven in the second shift pattern instead of the first shift pattern.

The clutch-to-clutch coast down shift determining means 164 determines from the second shift diagram of FIG. 8 based on the engine load (throttle valve opening θ _TH ) and the vehicle state represented by the vehicle speed V. Clutch to clutch Determines that the clutch downshift is during coasting. The sequence gear shift means 166 determines that the clutch-to-clutch coast down gear shift determination means 164 determines the 3 → 2 gear shift during coasting, that is, the clutch to clutch down gear shift from the second gear shift diagram selected by the gear shift pattern change means 162. If it is judged to be judged,
After the gear shift from the third gear to the first gear is executed, the gear shift from the first gear to the second gear is executed.

The vehicle speed determination means 168 determines whether the vehicle speed V has become equal to or lower than a preset low vehicle speed determination reference value A. The sequence speed changing means 166, after executing the speed change from the third speed gear to the first speed gear, makes the vehicle speed V equal to or lower than the low vehicle speed judgment reference value A preset by the vehicle speed judging means 168. If it is determined that the shift is made, the shift to the second gear is executed.

The drive traveling determination means 170 determines whether or not the vehicle is in the drive traveling state in which the engine load represented by the throttle valve opening degree or the output torque of the engine is a predetermined value or more. The sequence shifting means 166 is
Even when the vehicle speed determination means 168 does not determine that the vehicle speed V is equal to or lower than the preset low vehicle speed determination reference value A,
When the driving traveling determination means 170 determines that the vehicle is traveling, the shift to the second gear is executed.

FIG. 10 is a flow chart for explaining a main part of control operation of the electronic shift control device 78. In FIG. 10, in step (hereinafter step is omitted) SA1, after input signal processing such as reading various input signals is performed, in SA2, the shift lever 72 is moved to D.
It is determined whether the operation has been performed to the range. This SA
When the determination of 2 is denied, after the shift control of another range is executed in SA3, this routine is ended. In the shift control of other ranges, the shift lever 7
2 is the 4th range, the 3rd range, the 2nd range and the L range, the shift is controlled from the shift diagram, the solenoid valve S4 for generating the engine braking action is driven, and the gear stage is set according to each range. The change range of is limited.

If the determination at SA2 is affirmative, at SA4 corresponding to the low drive torque start determination means 160, the low drive torque start mode for starting the vehicle at the low drive torque by the second gear is set. Whether or not it is selected is determined based on the signal from the snow mode selection switch 77. If the determination in SA4 is negative, the normal speed change mode is set, and therefore, in SA5, D
After the normal shift control in the range is executed, this routine is ended. In this normal shift control, the shift is automatically controlled based on the actual throttle valve opening θ _TH and the vehicle speed V from the first shift diagram of FIG.
Since the vehicle is driven according to the shift pattern, the clutch-to-clutch down shift during coasting, in which shift control is relatively difficult, is avoided in the low throttle region.

When the determination at SA4 is affirmative, at SA6 corresponding to the shift pattern changing means 162, the second shift diagram is selected in place of the first shift diagram used up to that point. . Then, S corresponding to the clutch to clutch clutch downshift determination means 164.
In A7, whether the shift determined based on the second shift diagram is the 3 → 2 shift during coasting, that is, the clutch-to-clutch coast down shift, for example, 3 →
Judgment is made based on the throttle valve opening θ _TH at the time of 2-shift judgment.

If the determination at SA7 is negative, S
After the shift control based on the second shift diagram when the low drive torque starting mode is selected is executed in A8, this routine is ended. In this shift control, since the shift is automatically controlled based on the actual throttle valve opening θ _TH and the vehicle speed V from the second shift diagram of FIG. 8, the vehicle is made to travel in the second shift pattern. , 3 when coasting →
A 3 → 2 shift other than the 2 shift, that is, a clutch-to-clutch down shift is allowed. In the present embodiment, the SA5 and SA8 correspond to the shift control means 158.

However, if the determination at SA7 is affirmative, the vehicle speed determination means 168 is executed after the 3 → 1 shift from the third gear to the first gear is executed at SA9.
At SA10 corresponding to, it is determined whether the vehicle speed V is equal to or lower than a preset low vehicle speed determination reference value A. The low vehicle speed determination reference value A is set to a value close to the zero vehicle speed at which the vehicle hardly travels. Initially, the determination at SA10 is denied, so at SA11 corresponding to the drive traveling determination means 170, the throttle valve opening θ _TH is the determination reference value B or more to determine whether the vehicle is in the traveling traveling state. It is judged based on whether or not. Then, if the determination in SA11 is negative, this routine is ended.

While the above steps are repeatedly executed, if the determination at SA10 is affirmative, the vehicle speed V has decreased to near zero vehicle speed, so at SA12, the first gear to the second gear is selected. The 1 → 2 shift to the gear is executed. Even if the determination of SA10 is negative, if the determination of SA11 is positive, SA12
In the 1-to-2 shift is executed from the first gear to the second gear. In this embodiment, the SA9 and the S
A12 corresponds to the sequence shifting means 166.

As described above, according to this embodiment, when it is determined by SA4 corresponding to the low drive torque start determination means 160 that the low drive torque start mode is selected, the shift pattern changing means 162 is notified. By the corresponding SA6, the second shift diagram of FIG. 8 is selected instead of the first shift diagram of FIG. 7, and the second shift pattern is selected instead of the first shift pattern. Then, the SA9 and SA12 corresponding to the sequence speed change means 166 determine from the second shift line diagram that the clutch-to-clutch down shift from the third speed gear stage to the second speed gear stage during coasting. In this case, the gear shift from the third speed gear to the first speed gear is executed and then the speed change to the second speed gear is executed. Therefore, during normal traveling in which the low drive torque starting mode is not selected, the gear shift is executed based on the first gear shift diagram, so clutch-to-clutch down gear shift is avoided as much as possible to ensure drivability. On the other hand, when the low drive torque start mode is selected, the shift is executed based on the second shift diagram, and the clutch-to-clutch down shift during coasting is allowed, so that the low drive torque start is performed. The clutch-to-clutch down shift is enabled, and the sequence shift means 166 shifts the gear from the third speed to the first speed and then shifts to the second speed. As a result, the shift shock and the decrease in drivability resulting from it are eliminated.

Further, according to the present embodiment, the vehicle speed determining means 1
When it is determined in SA10 corresponding to 68 that the vehicle speed V has become equal to or lower than the preset low vehicle speed determination reference value A, SA12 corresponding to the sequence speed changing means 166 shifts from the third gear to the first gear. Since the shift from the first gear to the second gear after the shift is executed, there is an advantage that the second gear can be reliably established before the vehicle stops.

Further, in the present embodiment, the driving traveling determination means 1
When it is determined in SA11 corresponding to 70 that the vehicle is driving, S corresponding to the vehicle speed determination means 168 is determined.
Even when it is determined in A10 that the vehicle speed V is not equal to or lower than the preset low vehicle speed determination reference value A, the SA12 corresponding to the sequence speed changing means 166 shifts from the third speed gear to the first speed gear. Since the gear shift from the first gear to the second gear after the gear shift is executed, if the accele pedal is depressed during traveling in the low drive torque start mode, the vehicle speed is set to a predetermined low vehicle speed reference value. There is an advantage that the vehicle can be immediately started in the second gear without waiting for the following.

Although one embodiment of the present invention has been described in detail with reference to the drawings, the present invention can be implemented in other modes.

For example, in the embodiment of FIG. 10 described above, it does not matter if SA10 and SA11 are removed. In this case, the sequence speed changer 166 executes the change from the third speed gear to the first speed in SA9, and then immediately executes the change from the first speed to the second speed in SA12. .

Further, in the above-described embodiment, the coasting of the vehicle is performed.
During dynamic driving, the throttle valve opening θ _THIs less than a specified value
Small drive state and throttle valve opening θ_THIs non-zero
It refers to a coasting state like a driving state and actively accelerates.
The driving run in which the work is being performed is excluded.

Further, the low drive torque start determination means 160 of the above-described embodiment determines the selection of the low drive torque start mode based on the operation of the snow mode selection switch 77. The selection of the low drive torque starting mode may be determined based on the operation of a switch having another name such as a road starting switch.

Further, in the above-described embodiment, the automatic transmission 14
Although the third speed, the second speed, and the first speed are described as corresponding to the first speed, the second speed, and the third speed in the claims, , Other gears of the automatic transmission 14, for example, fourth gear, third gear, second gear
The high speed gear may correspond to the first gear, the second gear, and the third gear in the claims.

Further, the shift pattern changing means 162 described above.
(SA6) is the second shift diagram of FIG. 8 instead of the first shift diagram of FIG. 7.
Although the second shift pattern is selected instead of the first shift pattern by selecting the shift diagram, the throttle valve opening θ _TH or the vehicle speed V can be changed using the same shift diagram. Is added to the input signal to change the shift determination so that the result is the second shift pattern, or a part of the second downshift line is used for the first downshift determination. By using it, it may be configured to result in the second shift pattern.

Although not specifically exemplified, the present invention can be implemented in various modified and improved modes based on the knowledge of those skilled in the art.

[Brief description of drawings]

FIG. 1 is a skeleton diagram illustrating a configuration of an automatic transmission for a vehicle in which a gear position is controlled by a shift control device according to an embodiment of the present invention.

FIG. 2 is a table showing a relationship between a combination of operations of a plurality of frictional engagement devices and a gear established by the combination in the automatic transmission of FIG. 1;

FIG. 3 is a block diagram including a hydraulic control circuit and an electric control circuit for controlling the automatic transmission of FIG. 1;

FIG. 4 is a diagram illustrating an operation position of a shift lever of FIG. 3;

5 is a diagram illustrating a main part of the hydraulic control circuit of FIG.

FIG. 6 is a diagram illustrating a main part of the hydraulic control circuit of FIG. 3;

7 is a diagram showing a first shift diagram used in the shift electronic control device of FIG. 3. FIG.

FIG. 8 is a diagram showing a second shift diagram used in the shift electronic control device of FIG. 3;

9 is a functional block diagram illustrating a main part of a control function of the electronic shift control device of FIG.

10 is a flowchart illustrating a main part of a control operation of the shift electronic control device of FIG. 3;

[Explanation of symbols]

14: Automatic transmission 158: Shift control means 160: Low drive torque start determination means 162: Shift pattern change means 164: Clutch to clutch coast down shift determination means 166: Sequence shift means

Claims (1)

[Claims] Claim: What is claimed is: 1. By releasing the hydraulic pressure of one of the friction engagement devices and simultaneously increasing the hydraulic pressure of the other friction engagement device, from a predetermined first gear stage to a second gear stage that is one step lower than that. In a vehicle automatic transmission in which a clutch-to-clutch down shift is performed, a shift control device including shift control means for performing a shift determined based on an actual vehicle traveling state from a preset shift diagram. If the low drive torque start mode is selected by the low drive torque start determination means and the low drive torque start determination means, it is determined that the low drive torque start mode is selected. During the predetermined traveling, instead of the first shift pattern for downshifting from the first gear to the third gear one step lower than the second gear, also during the predetermined traveling The shift pattern changing means for selecting a second shift pattern for performing clutch-to-clutch down shifting from the first gear to the second gear, and the second shift pattern selected by the shift pattern changing means, When the clutch-to-clutch down shift from the first gear to the second gear is determined during the predetermined traveling, the shift from the first gear to the third gear is performed. A shift control device for an automatic transmission for a vehicle, comprising: a sequence shift means for performing a shift to the second gear after the shift is performed.